Improve the detection of folders

package.json

@@ -47,9 +47,9 @@
     "@types/tus-js-client": "^1.8.0",
     "@vue/cli-plugin-typescript": "^4.1.0",
     "@vue/cli-plugin-unit-jest": "^4.1.0",
-    "@vue/cli-service": "^4.1.0",
+    "@vue/cli-service": "^4.2.3",
     "@vue/test-utils": "1.0.0-beta.29",
-    "node-sass": "^4.12.0",
+    "node-sass": "^4.13.1",
     "prettier": "1.19.1",
     "sass-loader": "^8.0.0",
     "tus-js-client": "^1.8.0",

src/lib/drop-handler.ts

@@ -1,6 +1,6 @@
 export function getFilesFromDroppedItems(dataTransfer: DataTransfer): Promise<File[] | FileList> {
   return new Promise((resolve) => {
-    if (!includesFolder(dataTransfer.files)) {
+    if (!includesFolder(dataTransfer)) {
       return resolve(dataTransfer.files);
     }
     const files: File[] = [];
@@ -74,12 +74,26 @@ function getEntries(entry: any): Promise<File[]> | undefined {
   });
 }
 
-function includesFolder(files: FileList): boolean {
-  if (!files.length) {
+function includesFolder(transfer: DataTransfer): boolean {
+  if (!transfer.files.length) {
     return true; // if dropping only folders, no files will exist
   }
+
+  // Loop through the dropped items and log their data
+  for (const item of transfer.items) {
+    if (item.webkitGetAsEntry != null) {
+      const entry = item.webkitGetAsEntry();
+
+      if (entry && entry.isDirectory) {
+        return true;
+      }
+    }
+  }
+
+  const files: FileList = transfer.files;
+
   // tslint:disable-next-line
-  for (var i = 0; i < files.length; i++) {
+  for (let i = 0; i < files.length; i++) {
     // A folder has no type and has a size that is a multiple of 4096
     if (!files[i].type && files[i].size % 4096 === 0) {
       return true;

tsconfig.json

@@ -13,6 +13,7 @@
     "baseUrl": ".",
     "declaration": true,
     "declarationDir": "types",
+    "downlevelIteration": true,
     "types": [
       "webpack-env",
       "jest"